Mycotoxins are naturally occurring secondary metabolites produced by different fungi and are known to contaminate many commonly grown crops. These toxins are known to impact growth performance and health of animals and humans that consume contaminated materials. Mycotoxins having the most impact on animal production include aflatoxins, deoxynivalenol, T-2 toxin, zearalenone, ochratoxin A, fumonisins, and ergot alkaloids. One of the most common of these is aflatoxin, a known toxin and potent carcinogen. It is produced during drought conditions, and results from the growth of Aspergillus flavus and/or Aspergillus parasiticus. Aflatoxin concentrations are highly regulated in both human and animal nutrition, as aflatoxin B1 is one of the most potent hepatocarcinogens known. Ingestion of aflatoxins by livestock species is typically accompanied by a reduction in feed intake and a correlated reduction in growth rate.
Processing of agricultural commodities that have been contaminated with mycotoxins result in a concentration of the toxins in certain co-products and by-products and frequently these toxins concentrate in protein-containing streams. These toxins, while not intimately associated with the protein fractions, tend to follow these proteins during the normal processing schemes in place for grains and legumes. In the case of corn wet milling, many of these fungal toxins are concentrated in the corn gluten meal co-product, while concentrations remain lower in corn germ and corn fiber fractions. In contrast, the processed starch fraction is practically devoid of toxins. In the case of corn dry milling, toxins are concentrated in the distillers grains. This concentrating effect can result in toxin concentrations three (3) to ten (10) times that of the agricultural commodity prior to processing. Currently the United States Food and Drug Administration (FDA) Compliance Policy Guide Sec. 683.100 provides action levels for aflatoxins in animal feeds. Listed below are the FDA action levels for aflatoxins in animal feeds at the time of filing this application:
TABLE 1Acceptable aflatoxin levels in animal feedsAflatoxin,ppbUses20For corn and other grains intended for immature animalsincluding immature poultry) and for dairy animals, or whenits destination is not known20For animal feeds, other than corn or cottonseed meal100For corn and other grains intended for breeding beef cattle,breeding swine, or mature poultry200For corn and other grains intended for finishing swine of 100pounds or greater300For corn and other grains intended for finishing (i.e. feedlot)beef cattle and for cottonseed meal intended for beef cattle,swine or poultry
Corn gluten meal is one of the common co-product ingredients produced by corn wet mills that experiences a significant increase in mycotoxin concentration compared to the grain from which it was derived. As an example, the concentrating effects of aflatoxin in corn gluten meal results in greater than 20 ppb concentrations of aflatoxin on a dry weight basis when the incoming corn grain has almost negligible (<5 ppb) concentrations of aflatoxin. Contaminated corn gluten meal is substantially discounted when aflatoxin concentration is greater than 20 ppb resulting in significant financial loss for corn processing plants faced with mycotoxin challenges.
The animal feed industry has long been aware that bentonite products, hydrated sodium/calcium aluminosilicates (HCAS), and activated charcoals have adsorbing and binding characteristics with respect to certain mycotoxins and thus their use may alleviate mycotoxin effects on feed intake, growth or lactation performance of livestock. However, from a regulatory perspective, the act of adding a mycotoxin adsorbent to a contaminated feedstuff does not in itself guarantee that the mycotoxin contaminant is rendered harmless. Therefore, adding an adsorbent to a production process without removing the adsorbent and adsorbed toxin does not address the problems associated with the toxin. Additionally, the US FDA currently has not approved the use of mycotoxin adsorbent agents as feed ingredients, although several of the products commonly used for this purpose in other areas of the world are approved as flowability enhancers in the United States.
In an attempt to remediate toxins by adsorption, the United States Department of Agriculture developed a process to produce a detoxified peanut protein concentrate. In this process, a bentonite adsorbent and enzymes are used in peanut processing to limit the toxin concentration in a fractionated protein stream, as described in Davis, et. al. U.S. Pat. Pub. No. 2011/0014319 A1. In this approach, the clay is admixed with enzyme hydrolyzed peanut meal liquid followed by centrifuging to create a fraction containing a toxin-reduced soluble protein hydrolysate, and an insoluble protein containing the clay-adsorbed toxin. Whereas the soluble protein is recovered in the supernatant and is substantially free of aflatoxin and bentonite clay, the insoluble fraction containing the bentonite clay and toxin is substantially enhanced in toxin content. The insoluble protein fraction would therefore be restricted as a feed ingredient even if the toxin was ostensibly biologically inactivated via adsorption or not detectable using certain analytical techniques.